Impact extrusion process and blank for use therein



y 9, 1968 E. A. DONEGAN 3,391,563

IMPACT EXTRUSION PROCESS AND BLANK FOR USE THEREIN Filed Sept. 7, 1965 2 Sheets-Sheet l n 0 a 2M n 2:, m R

y 1968 E. A. DONEGAN 3,391,563

IMPACT EXTRUSION PROCESS AND BLANK FOR USE THEREIN Filed Sept. 7, 1965 2 Sheets-Sheet 2 J? i I fi \& 7% I 7.

I/Wem or fdwarcl ,4. fionegan United States Patent 6 Claims. (a. 72-2ss ABSTRACT OF THE DISCLOSURE A method of impact extrusion of ductile metal to form a tube, and a blank for use in this method. The blank consists of an annular pellet of ductile Zircaloy with inner and outer cylindrical sheaths of copper. The blank is rapidly extruded by the end pressure of a tool surface (with a further tool supporting the inner sheath) to form an elongated Zircaloy tube with inner and outer copper skins.

This invention relates to improvements in hot impact extrusion techniques and is more specifically concerned with an improved manner of forming a work blank and of arranging the same in an impact extrusion press.

In one aspect the invention is concerned with an improved method of forming a tube from a ductile metal (for example, Zircaloy), such method comprising:

(i) Forming a blank comprising (a) An axially elongated annular pellet of said ductile metal,

(b) A metal collar secured coaxially to a first end of said pellet,

(c) A cylindrical outer sheath of copper tightly engaging the outer surface of said pellet to encase the same, and extending beyond the Second end thereof to form an inwardly projecting flange,

((1) And an inner tubular sheath of copper extending coaxially through and firmly engaging said pellet, said tube having an end portion formed into an outwardly projecting flange,

(ii) Mounting said blank as a snug fit in a cylindrical die having an inwardly and downwardly inclined annular surface, with said outer sheath resting on said surface,

(iii) Striking said collar with an annular tool surface while introducing a cylindrical tool portion into said inner sheath to support the same, to extrude said ductile metal and said sheaths through an orifice formed between said die and said cylindrical tool portion. The invention is also concerned with the blank itself and in this aspect comprises (a) An axially elongated annular pellet of Zircaloy,

(b) A metal collar secured coaxially to a first end of said pellet,

(c) A cylindrical outer sheath of copper tightly engaging the outer surface of said pellet to encase the same,

((1) And an inner sheath of copper extending coaxially through and firmly engaging said pellet.

The inner and outer copper cladding represented by the inner and outer sheaths flows with the ductile Zircaloy metal while acting as a lubricant therefor, the orifice formed between the die and the cylindrical tool portion resulting in the formation of a product with the desired properties.

One manner of carrying the invention into practice is illustrated in the accompanying drawings. It is to be understood that these drawings are provided by way of example only, and not by way of limitation of the scope of the invention, which is defined in the appended claims.

ice

In the drawings:

FIGURE 1 is a first view, in exploded form, of the two main parts of an impact extrusion press and a work blank therebetween;

FIGURE 2 shows the blank located in the die with the parts of the press being brought together;

FIGURE 3 is an enlarged view of the die and blank of FIGURE 2;

FIGURE 4 is a view similar to FIGURE 2 showing a later stage in the process; and

FIGURE 5 is a view similar to FIGURE 2 showing the final stage in the process.

FIGURE 1 shows the two relatively movable parts 10 and 11 of an impact extrusion press, the upper part 10 carrying a cylindrical tool 12 having a tool surface 12a and a central protruding cylindrical tool portion 13. The lower press part 11 supports a die 14 from which depends a tube 15 containing an ejector rod 16. Also shown in FIGURE 1 is a work blank 17 comprising an annular pellet 18 of the ductile Zircaloy metal to be extruded; a collar 19 of steel secured to the upper end of the pellet 18; an outer cylindrical sheath 20 of copper projecting beyond the lower end of the pellet 18 and having an inturned flange portion 21 at the bottom; and an inner copper tubular sheath 22 which projects beyond the ends of the pellet 18 and is formed with an outturned lower flange 28 and upper flange 29. The sheaths 20 and 22 both tightly engage the pellet 18-.

The blank 17 is placed in the die 14 as a snug fit, as indicated in FIGURES 2 and 3. The die has an inwardly and downwardly inclined annular surface 23 terminating in a lower edge 24 below which the metal is relieved at 25, so that the edge 24 represents a very slightly projecting lip. FIGURE 2 shows the manner in which the flange 21 portion of the blank 17 seats on the surface 23.

The tool 12 is now caused to descend rapidly in the usual manner of an impact extrusion press, the parts being shown thus coming together in FIGURE 2. FIG- URE 4 shows the conditions when the parts have come fully together, and FIGURE 5 demonstrates the manner in which the downward pressure of the tool surface 12a acting through the collar 19 forces the ductile metal 18 and its inner and outer sheaths out of the space be tween the lip 24 and the tool portion 13, causing both metals to flow downwardly and form the desired product, an elongated tube 27.

The product is a tube of composite material consisting of an outer and an inner skin of copper bonded to a Zircaloy tube.

Use of the collar 19 of a cheaper metal is not essential to the operation, but is preferably used to improve utilisation of the costly Zircaloy material by substitution of the cheaper material as most of the flange left at the upper end after extrusion.

I claim:

1. A blank for use in a hot impact extrusion process, comprising:

(a) an axially elongated annular pellet of ductile metal,

(b) a metal collar secured coaxially at a first end of said pellet,

(c) a cylindrical outer sheath of copper tightly en gaging the outer surface of said pellet to encase the same,

(d) and an inner sheath of copper extending coaxially through and firmly engaging said pellet.

2. A blank according to claim 1, wherein an end of said outer sheath projects beyond the second end of said pellet, such projecting sheath end including an inwardly inclined flange portion.

3. A blank according to claim 2, wherein both ends of said inner sheath project beyond the ends of said pellet to form outwardly projecting flanges.

4. A blank according to claim 1, wherein the ductile metal is Zircaloy.

5. A method of forming a tube by impact extrusion of ductile metal, comprising:

(i) forming a blank comprising- (a) an axially elongated annular pellet of said ductile metal,

(b) a metal collar secured coaxially at a first end of said pellet,

(c) a cylindrical outer sheath of copper tightly engaging the outer surface of said pellet to encase the same, and extending beyond the second end thereof to form an inwardly projecting flange,

(d) and an inner tubular sheath of copper extending coaxially through and firmly engaging said pellet, said tube having an end portion formed into an outwardly projecting flange,

(ii) mounting said blank as a snug fit in a cylindrical portion. 6. A method according to claim 5, wherein said ductile metal is Zircaloy.

References Cited UNITED STATES PATENTS Witte 29-490 Arness 29190 Braun et al. 29-190 Carlson 29190 20 RICHARD O. DEAN, Primary Examiner.

DAVID L. RECK, Examiner. 

